package com.rising.face.nio.groupchat;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.nio.charset.StandardCharsets;
import java.util.Iterator;

/**
 * @Author: rising
 * @Description:
 * @Date: create in 2021/1/23 17:51
 */
public class GroupChatServer {

    //定义属性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 6667;

    //构造器
    public GroupChatServer() {
        try {
            //得到选择器
            selector = Selector.open();
            //ServerSocketChannel
            listenChannel = ServerSocketChannel.open();
            //绑定端口
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            //设置非阻塞模式
            listenChannel.configureBlocking(false);
            //将改listenChannel 注册到selector
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);

        } catch (Exception e) {

        }
    }

    //监听
    public void listen() {
        try {
            //循环处理
            while (true) {
                int count = selector.select();
                if (count > 0) {//有事件处理
                    //遍历得到selectionKey集合
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while (iterator.hasNext()) {
                        //取出selectionKey
                        SelectionKey key = iterator.next();
                        //监听到accept
                        if (key.isAcceptable()) {
                            SocketChannel sc = listenChannel.accept();
                            sc.configureBlocking(false);
                            sc.register(selector, SelectionKey.OP_READ);
                            //提示
                            System.out.println(sc.getRemoteAddress() + " 上线");
                        }

                        if (key.isReadable()) {//通道发生read事件，即通道可读的状态
                            //处理读（专门写方法）
                            readData(key);
                        }
                        //当前的key删除，防止重复处理
                        iterator.remove();

                    }
                } else {
                    System.out.println("等待。。。。");
                }
            }
        } catch (Exception e) {

        } finally {

        }
    }

    //读取客户端消息
    private void readData(SelectionKey key) throws IOException {
        //定义一个SocketChannel
        SocketChannel channel = null;
        try {
            //得到channel
            channel = (SocketChannel) key.channel();
            //创建buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);

            int count = channel.read(buffer);

            //根据count的值做处理
            if (count > 0) {
                //把缓冲区的数据转成字符串
                String msg = new String(buffer.array());
                //输出该消息
                System.out.println("from 客户端：" + msg);

                //向其他的客户端转发消息(去掉自己)，专门写一个方法来处理
                sendInfoOtherClients(msg, channel);
            }

        } catch (Exception e) {
            System.out.println(channel.getRemoteAddress() + " 离线了。。。。。。。");
            //取消注册
            key.cancel();
            //关闭通道
            channel.close();
        }
    }

    //转发消息给其他客户（通道）
    private void sendInfoOtherClients(String msg, SocketChannel self) throws IOException {
        System.out.println("服务器转发消息中。。。。");
        //遍历所有注册到selector上的socketChannel，并排除self
        for (SelectionKey key : selector.keys()) {
            //通过key取出对应的SocketChannel
            Channel targetChannel = key.channel();

            //排除自己
            if (targetChannel instanceof SocketChannel && targetChannel != self) {
                //转型
                SocketChannel dest = (SocketChannel) targetChannel;
                //将msg存储到buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //将buffer的数据写入通道
                dest.write(buffer);
            }
        }

    }
    public static void main(String[] args) {
        new GroupChatServer().listen();
    }

}
